The present invention generally relates to power source control apparatuses, and more particularly to a power source control apparatus for automatically turning ON/OFF a power source of a display unit depending on the existence of an input signal.
Recently, computers, personal computers and the like (hereinafter simply referred to as main bodies) are more frequently operated unattended in a continuous manner. For this reason, in order to prevent burnout and extend the serviceable life of a cathode ray tube (CRT) which is connected to the main body during the unattended operation, there are demands to turn OFF a CRT power source. In this case, the main body operates even if the CRT power source is turned OFF.
Conventionally, an input signal from an input device such as a keyboard is monitored, and the CRT power source is turned OFF if the input signal is not received for a predetermined time. The CRT power source is turned ON when the input signal is detected.
But when turning ON the CRT power source when the input signal is detected, it is necessary to display the state of the main body at the time when the CRT power source is turned ON, because the main body continues to operate even while the CRT power source is OFF. Hence, according to the conventional method of turning ON the CRT power source when the input signal is detected, the input signal is transmitted to the main body in addition to turning ON the CRT power source when the input signal is detected.
As described above, the main body continues to operate even while the CRT power source is OFF. For this reason, if the input signal is input from the keyboard, a software of the main body will operate in response to this input signal. Therefore, if the CRT power source is turned ON by generating the input signal by manipulating an arbitrary key of the keyboard, a mouse or the like in the state where the CRT power source is OFF, the state of the main body at the time when the CRT power source is turned ON is not correctly displayed on the CRT. In other words, the actual display on the CRT relates to the state of the main body which carries out an erroneous operation in response to the input signal.